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Organization of DNA

Organization of DNA. Genome*. the complete genetic makeup of an organism, its total DNA sequence. Genes*. units of heredity that are passed on from parent to offspring determine, in whole or in part, a genetic trait segments of DNA responsible for the production of a functional protein

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Organization of DNA

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  1. Organization of DNA

  2. Genome* the complete genetic makeup of an organism, its total DNA sequence

  3. Genes* • units of heredity that are passed on from parent to offspring • determine, in whole or in part, a genetic trait • segments of DNA responsible for the production of a functional protein • every person has two copies of each gene, one inherited from each parent

  4. Complexity and Genome • No correlationbetweencomplexity of organism and … • # of protein-codinggenes (rice) • genome size (examplelungfish) • # of protein-codinggenes and genome • size • genes are not evenlyspreadalong • chromatin or chromosomes

  5. Organization of genetic information* • Viral • RNA or DNA, ss or ds, linear or circular • Bacterial • DNA, ds, usuallycircular • found in one area = nucleoid • often have Plasmids (small extra- chromosomal DNA) • Eukaryotic • DNA, ds, lineards =double-stranded, ss=single-stranded

  6. Eukaryotic chromosomes Because we have A LOT of DNA in each cell it needs to be packaged in a specific way

  7. Packing of DNA into chromosomes (1)* Level 1 Winding of DNA around histones to create a nucleosome structure. Level 2 Nucleosomes connected by strands of linker DNA like beads on a string.

  8. Packing of DNA into chromosomes (2)* Level 3 Packaging of nucleosomes into 30-nm chromatin fiber. Level 4 Formation of looped domains.

  9. Packing of DNA into Chromosomes (big picture)

  10. Packing of DNA into Chromosomes (big picture)

  11. Isn’t that a lot of proteins ?* Chromatin: - about twice as much protein as DNA Two major types of proteins: Histones Non-histones

  12. Isn’t that a lot of proteins ? • Two major types of proteins: • Histones • abundant, basic proteins with a positive charge that bind to DNA • evolutionarily conserved 2. Non-histones - all the other proteins associated with DNA • - differ markedly in type and structure

  13. Your Chromosomes • Chromosomes are compact molecules of DNA • A human set of chromosomes contains 23 pairs • 23rdpair are your sex chromosomes • Karyotype • http://www.youtube.com/watch?v= • ubq4eu_TDFc&list= • PLF9969C74FAAD2BF9&index=1

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